WTF?? Piece of metal in oil pan???

[rrubel]

Today's project was removing the oil pan to replace the torn gasket (don't ask...). As I was draining the last bit of oil from the bottom after removing it, I noticed something shiny and pulled it out. Darned if it didn't look like a piece of piston skirt! A bit beat up, but with ridges along one side and slightly curved. Maybe an inch long by half an inch wide. I took a look best I could at the bottoms of the pistons while underneath the car; I couldn't see anything apparently missing (these are strange skirts, though, almost coming to a point in two places on each piston) but only had a good view of 5 of the 8.

I guess it's possible that a piston (or two, or more) had been replaced over the years and that this is from an old one, but still... this is worrying. I cannot at this point pull the engine and get a rebuild for several reasons.

I saw no pieces of metal shavings or anything but this one piece.

Any thoughts, good bad or indifferent?
Thanks.
[RICHR]

 

[cntrhub]

Seems you kind of know the history of the car? There is no other way around removing pistons, but to drop the oil pan to remove the con-rod caps. I'm sure if you saw that piece in the pan, the person working on the pistons would surly have found it also. Since you didn't have a good look at the other pistons, I would assume it is from one of the pistons you couldn't see. That piston now has stress risers (cracks forming) and will eventually crack some more.

 

[vader86]

id be scared to death

 

[86PACER]

Darned if it didn't look like a piece of piston skirt! A bit beat up, but with ridges along one side and slightly curved. Maybe an inch long by half an inch wide.
[RICHR]

:eek That is scary. I sure hope it does not turn out to be the worst for you. Good luck

 

[rrubel]

Cntrhub, I don't know much history before the previous owner but the last two owners were weekend-driver older folks. First owner, though, may have raced the car. I know the engine has been opened several times (by the layers of gasket material I see everywhere) but I have no service history other than some intake work.

What could cause a small piece of piston skirt to break off??
[RICHR]

 

[vader86]

lots of high rpm driving would put alot of stress on the pistons and rods overall, that would be the only good reason for it to just break off

 

[Hib Halverson]

If you have conclusively ID's the debris as a section of piston skirt, there's a good chance that same piston or others may be cracked. Unless you can
positively identify this piece as being left in the pan from a previous repair, I would not continue to run the engine without repairs. If one skirt is broken others will follow. You could end-up experience a catistrophic engine failure.

I would pull the engine. Get all the pistons out. If the engine is low or modest mileage since new or last overhaul, obviously, scrap the piston that's broken and carefully inspect the others. There's a good chance you'll have others which are cracked. You can hone the bad holes and buy new pistons to replace those which have fractured or are cracked.

If the engine is high mileage, I'd just overhaul the engine.

Unless you can positively ID the piece as pre-existing debris, don't try to talk yourself into cleaning the pan out and continuing to run the engine.

 

[tnovot]

"I noticed something shiny and pulled it out. Darned if it didn't look like a piece of piston skirt! A bit beat up, but with ridges along one side and slightly curved."

Rich -
I just finished building an engine for my '23 T-bucket. I used a junkyard 350 4-bolt from a truck. The engine ran with with no strange noises prior to removal. When I pulled the pan, I found exactly the same size and shape piece. You are correct - it is a piece of piston skirt. Was no problem for me as I had already planned to go .030 over with all new pistons (and lots of other stuff) anyway.
Bad break! Probably something to do with Murphy's Law. I know it's very tempting to avoid more engine work. You have already put much time and expense into the top end of your engine. But, you are inviting disaster if you try to use this engine in its current state. All your previous engine work could be down the drain.
At the very least, take Hib's advice. It it were me, I'd replace ALL the pistons without question. You said you can't pull the engine at this time. Is it possible to just let it sit until you can do a rebuild?
Good Luck.
Terry

 

[rrubel]

AAARRRGGGGHHHHHHH. Is extreme cursing allowed here? $%()&*)$&&(@#^&^&*(#$^^^&#$^^&*(#^&^&^&*^&*(@({#*+)_()+#$

Ugh. That looks more like line noise than cuss words. Anyway...

Ok, off the oil pan comes again. This time I'll use a little mirror and inspect all the pistons. If one's busted, I guess I'll buy a roller short block, put everything on it outside the car, and swap engines. How much engine CAN I assemble on a stand? Everything but the exhaust? Can I leave the AC and PS stuff in place and move them out of the way to take out the block? If I went with a 383, would I have to get the heads redone again?

Guess I know where the income tax refund is going Anyone got a good deal on an 87-91 shortblock?

I guess I should feel happy that I discovered this now instead of later, if it truly is a problem. But somehow that doesn't make me feel better. Hib, the engine has 142000 miles on it. Not sure what, if anything, has been done to the bottom end. Oil pan gasket was not original, but that probably doesn't mean much. You need to pull the pan for the rear main seal, right? I know that's been replaced at least twice. And that kinda kills the "been sitting there" theory, doesn't it?

Thanks, guys. I've opened a serious Pandora's box here and I'll just have to deal with the consequences. Please keep the advice coming...
[RICHR]

 

[Hrtbeat1]

Not good my friend

Rich,

Please don't run that motor till you can get it rebuilt. I know you have done a lot of work to it and would hate to see it all go up in a cloud of smoke. The 383 short block would be the way to go IMHO, but I have seen aluminum short block 350's for just over 12 bills (or so they are advertised), check www.lakechevrolet.com click on parts, I don't know the actual availability but they should let you know. If you go this route let me know as I have been thinking of doing the same to mine ... you just can't get a better deal on an aluminum short block (if that is what they are really offering). Being a Chevy dealer their parts are warranted also ... just a thought.

 

[rrubel]

I think what I'm going to do is buy a rebuilt 350 short block (no 383 here... want power, but also want decent gas mileage and reliability/strength). I've found a couple shops that will buy the parts and assemble it (with complete block testing and cleaning) for around $1300 or so. Then I'll have it shipped here, install all the goodies I've got, and have the Vette and new engine rollbacked to my mechanic and have HIM do the actual swap. I think that's too much of a challenge for me, dealing with the transmission and stuff without a lift. Then I'll rollback the car home again and finish the rest of the engine work.

I'm definitely checking out any links you guys post; CorvetteForum.com has also given me a few, though mostly for complete crate motors - which I do not want.

So is the L98 a 2-bolt or 4-bolt main? Is the block the same as an LT1 block?

Thanks...
[RICHR]

 

[drags1998]

Hi Rich, I dont have any GOOD News for ya. First things First, MAKE SURE of what you got. If its a broken piston, With 142000 on the clock, its time to overhaul it.If you are going to use your heads over again,Have them checked,and reconed if needed. Everyone knows how expensive this can get,Its just not the time to cut corners. BEST OF LUCK!!!!!

 

[rrubel]

Fortunately, the heads (and pretty much everything ELSE outside of the short block assembly) are brand new. They're mounted, but never oiled or run. Heads, cam, and timing gears are all I've gotten reinstalled. The big advantage of getting a new block is that I can get a proper roller block instead of retrofitting my flat-tappet one (returning the retro roller lifters would net me almost a third of the cost of the new block!). At this point, I've resigned myself to the fact that I need an overhaul... and if I specify the right parts (forged vs cast pistons, for example) I should get a motor that's almost indestructable based on the power I plan to put through it.
[RICHR]